The session “Time-Lapse Imaging and Monitoring” was a highlight of SEG's 2001 Summer Research Workshop, Synergies in Geophysical, Medical, and Space Imaging, because it dealt with techniques that allow various types of image data to be effectively analyzed at repeated snapshot times. The potential payoffs for time-lapse monitoring are impressive—millions of dollars of additional production from oil fields, improved medical diagnoses, and the opportunity to observe important geologic processes on and beneath the earth's surface as they are occurring. This has perhaps been the ultimate dream of earth scientists ever since the origins of this discipline. The basic concept is...